The Perception Survey on the quality of life in European cities aimed at measuring local perceptions in 75 cities in the EU, Croatia and Turkey. The data are based on surveys/interviews of randomly selected citizens. The data have been extracted from the Eurostat database and joined with the corresponding city shapefile, subsequently been mapped as coloured dots.

The information is provided as « synthetic index ». From the perception survey data, an index was calculated by subtracting the negative answers from the positive ones and dividing the result by the total number of answers ("very much agree" and "quite agree" are counted as positive answers, whereas "very much disagree" and "quite disagree" are negative answers).This initial index has a minimum of -1 and a maximum of +1. To make it easier to use, the index was then multiplied by 50 and 50 then added to the result. The resulting index covers values between 0 and 100. A value above 50 means positive answers predominate; below 50, there are more negative answers.